I know there have been a couple posts related to this, but I've tested it many times and definitely am getting unexpected behavior.
When I wipe out all my preferences (delete the ~/Library/Application_Support/Adium_2.0 folder) and start fresh, everything works right. I can set the font and color in my message window, and the text that I type and send is the same size, shape, and color I want. This is also saved across sessions properly.
Then, if I start messing around with the default font size in the appearance preferences, something goes wrong, and from that point on, I can only change the color of the text I type. If I try to change the font, the second I start typing (or click inside the text entry box), the font inspector window automatically reverts back to the sticky value and everything I type is the same. I cannot change the sticky font anymore, at all.
If I choose "Restore Default Formatting" from the Format menu, my font will revert back to the style default (or always Helvetica, whatever it's supposed to do), and that becomes the sticky value. Every attempt to change the font I type just reverts back to default the second I press a key. Colors can still be changed, and are persistent.
If I nuke my library folder, it starts working again.
If you can't reproduce the problem, I'll try to help. Could you tell me what plist file contains the sticky font settings, so I can try and debug it better to find the exact cause? I still can't narrow down the exact point at which things go wrong (I only know it's once I fiddle with the message style and default view font).
Thanks!
Outgoing font won't stick
OK, so the problem isn't with the Formatting.plist file (with hindsight, I don't see why I would have suspected that in the first place). Needless to say, it remains correctly set to whatever Adium thinks the sticky font should be... it's not corrupted or anything, and the permissions are fine.
I did find the exact point at which the bug starts to appear. The outgoing font can no longer be changed once I set the default view font in the Messages preference pane. If I wipe out the library folder, the outgoing font works correctly until I try and override the default view font.
I have no idea why I would see this, when it should be easy to reproduce and affect lots of users. Any ideas on how I can try to debug or work around this? Are there any other persistent Adium files not in the Application Support folder I can try deleting? I have seen this behavior on 0.82 and 0.83b (it never used to happen on the 0.7x versions).
Also, I don't know if this should have anything to do with it, but for some reason I am getting strange font scaling behaviour. Even though I check the box to "Show received message fonts", Adium scales them down based on the default font size (I could swear that what I see on the screen is actually one size smaller than what I set as the default view size, but I could just be insane).
Here is what I actually see when I send a message to myself:

Thanks again for the help trying to solve this...
I did find the exact point at which the bug starts to appear. The outgoing font can no longer be changed once I set the default view font in the Messages preference pane. If I wipe out the library folder, the outgoing font works correctly until I try and override the default view font.
I have no idea why I would see this, when it should be easy to reproduce and affect lots of users. Any ideas on how I can try to debug or work around this? Are there any other persistent Adium files not in the Application Support folder I can try deleting? I have seen this behavior on 0.82 and 0.83b (it never used to happen on the 0.7x versions).
Also, I don't know if this should have anything to do with it, but for some reason I am getting strange font scaling behaviour. Even though I check the box to "Show received message fonts", Adium scales them down based on the default font size (I could swear that what I see on the screen is actually one size smaller than what I set as the default view size, but I could just be insane).
Here is what I actually see when I send a message to myself:
Thanks again for the help trying to solve this...
One more piece of info... rather than simply nuke the whole Adium 2.0 library folder, all I have to do is delete the "WebKit Message Display.plist" file. Once I do that, and restart Adium, outgoing fonts can be changed again, and are still persistent across sessions.
Even more specifically, I only need to delete the lines corresponding to the default view font for the current style, such as:
<key>com.adiumx.mockie.style:FontFamily</key>
<string>LucidaGrande</string>
<key>com.adiumx.mockie.style:FontSize</key>
<integer>14</integer>
Once those lines are gone, outgoing fonts are back to normal.
Even more specifically, I only need to delete the lines corresponding to the default view font for the current style, such as:
<key>com.adiumx.mockie.style:FontFamily</key>
<string>LucidaGrande</string>
<key>com.adiumx.mockie.style:FontSize</key>
<integer>14</integer>
Once those lines are gone, outgoing fonts are back to normal.